1. T Das, D Pal, G S Bisht, T K Bhattacharya, T K Maiti; Retention of Protein-Protein interactions in Microcontact Printing; Poster- Proceedings of International Symposium On Nano-Bio Interface-2006.
Abstract: Protein micro-arrays have evolved to become one of the most essential tools for proteomics. However, conventional commercial scale micro-arrays, mostly fabricated by spotting techniques, need sophisticated equipments that can be too expensive for production. A newly devised soft-lithography based method called Microcontact Printing (µCP) is essentially a cost-effective method that utilizes elastomeric, commonly Polydimethoxysiloxane(PDMS), stamps for printing. In the present work, PDMS stamps containing micropillars have been fabricated using Photolithography followed by Softlithography techniques. Three proteins - Bovine Serum Albumin, Concanavalin A and Abrus agglutinin have been micropatterned on the aldehyde activated glass coverslips and their mutual interactions have been studied. Results show that the printed proteins retain their selective interaction abilities.
2. G S Bisht, Manju Bansal; A Computational Investigation of Mg ADP Inhibition of F1-ATPase , Paper- International Symposium on Computational Biology and Bioinformatics-2006, Bhubaneshwar, India.
Abstract: Nature employs several biomolecular motors to carry out some of its very essential functions of life, out of which some have shown a potential for applications in nanotechnology. One of such proteins is F1-ATPase which has lately been hybridized with mechanical structures to rotate them using ATP as the fuel. F1 ATPase contains five different subunits with the stoichiometry α3 β3γδε, the central gamma rotor is surrounded by a hexagonal "stator "in which the three alpha and there beta subunits are arranged alternately. The catalytic sites are located at the interfaces between the beta and alpha subunits, mainly on the beta subunit, and are arranged 120 degrees apart around the gamma subunit. However its direct application in nanotechnology has seen some major hurdles, in spite of its promising abilities. Mg-ADP inhibition of F1-ATPase is one drawback that causes these motors to choke in the presence of ADP, a byproduct of ATP hydrolysis, and makes its consistent rotation difficult. The present paper discusses some computational techniques that can be used to investigate the Mg-ADP inhibition state of F1-ATPase and the mechanisms behind it. The models yet available for the operation of F1-ATPase in hydrolysis mode have been surveyed and focus has been zeroed in, onto the half closed conformation of beta subunit that F1-ATPase attains before ultimately falling into the inhibition state in presence of ADP. The inhibition state has been hypothesized to be a thermodynamically stable conformation, with support from existing models. Minimizations were run on the half closed conformation, the precursor to the inhibition state, with ADP docked into the appropriate binding site and minor conformational changes favoring stabilization of ADP docking was observed. It is thereby proposed to carry out MD simulations of this minimized structure to allowa conformational sampling of the final inhibition state. A binding energetics study has been proposed to establish the thermodynamic stability of the final inhibition structure concluded from MD simulations. Also TMD simulations have been proposed to investigate some of the hypothesize mechanisms of ADP inhibition.
3. Gobind S. Bisht, T.K. Bhattacharyya, Tamal Das, Debashish Misra, and T.K. Maiti; Role of Material Characteristics of Diamond-like Nanocomposite (DLN) thin films in tailoring its biocompatible properties, Submitted to Journal of Biomedical Materials Research Part B: Applied Biomaterials.
Abstract: The aim of the present work is to experiment with novel material designs of Diamond-like Nanocomposite (DLN) thin films with low internal stress and better biocompatibility and reveal the underlying principles behind the role of its physiochemical characteristics in tailoring its biocompatibility. For this purpose, films were synthesized with different compositional network properties, achieved through different ratios of Silazane and Siloxane precursors. DLN 704 and DLN 0502 were studied as representatives of the two class of samples prepared. The material characterization using FTIR and GIXRD revealed an amorphous multiphase interpenetrating network comprising of amorphous SiC, SiN, SiO in a diamond like carbon matrix which implicates reduction of internal stress in the DLN film and improvement in adhesion strength. Additionally stress reduction was also achieved through embedded nanoparticles in some cases as shown by High Resolution Tramission Electron Microscopy (HRTEM). AFM surface topography unveils a rough surfaces for DLN 704 compared to DLN 0502. Protein adsorption study of Bovine Serum Albumin (BSA) using AFM discloses a complete cover of multilayer protein adsorbed on DLN 0502 surfaces while DLN 704 show only partial cover. Cell experiments with L929 fibroblast cells show good cell spreading and attachment for DLN 0502 compared to DLN 704 and glass. DLN 0502 is believed to be an excellent biomaterial with low internal stress (by the virtue of a quad-phase interpenetrating network) attributed to good adhesion strength; and shows high biocompatibility.
4. G Teixidor, R Gorkin, G S Bisht, M Kulkarni, P Tripathi, J
Subramaniam, T Maiti, T Battacharyya, A Sharma, B Y Park, Marc Madou; Carbon
micro-arrays as a substrate for patterned cell growth:Submitted to Journal of Biomedical Materials Research.
Abstract: The study of the biocompatible properties of Carbon-MEMS shows that this new microfabrication technique is a very promising approach to be used as a platform for the study of cell physiology. Four different types of substrates were tested, namely, C-MEMS on silicon and quartz wafers, indium tin oxide on glass and oxygen-plasma treated carbon thin films. Two cell lines, murine dermal fibroblasts (MDF) and neuroblastoma spinal cord hybrid cells (NSC-34) were plated onto the substrates. Both cell lines showed preferential adhesion to the selectively plasma treated regions. The analysis with AFM and FTIR demonstrated that oxygen plasma treatment modifies the physical and chemical properties of carbon films, which plausibly enhances the adsorption of extracellular matrix forming proteins on its surface. This accounts for the differential adhesion of cells on the plasma-treated areas. These results will be used in the future design of novel biochemical sensors, drug screening systems and basic cell physiology research devices.
5. G S Bisht, T Das, D Mishra, S K Mallick, T K Bhattacharya, T K Maiti; Material and Biological characterization of Diamond-like Nanocomposite films; Poster - International Conf. on Design of Biomaterials-2006. : BIND-06 & XVII Annual Meeting of SBAOI (Society of Biomaterials and Artificial Organs), IIT Kanpur, India.
Abstract: Diamond-like Nanocomposites (DLN) are amorphous, hard and wear resistant materials which are composed of two interpenetrating networks, one being a diamond-like carbon C-H.network (composed of sp2 and sp3 hybridized carbons) and the other being a glass-like a Si-O/Si-N network. This specific structure leads to lower internal stress, better adhesion and higher temperature stability on a wide array of substrates ranging from glass to gold. DLN films were deposited on pyrex glass using proprietary PECVD technique with siloxane and silazane precursors under different conditions and their material properties characterized for applications in biomaterials. The materials are different in terms of the proportions of the mixture of Silazane and Siloxane precursors used as well as doping with O2; which leads to further interpenetration of the Si-O and C-H networks with Si-Nx and SiONx type networks. This was indicated by ATR Fourier transform Infrared spectroscopy and the bulk amorphosity of the films was confirmed using grazing incidence XRD at an incidence angle of 2º. Surface topographical study using Atomic Force Microscopy showed interaction of nanoscale surface features like Clustered Nucleation Sites (CNS), with Bovine Serum Albumin (protein).Some biocompatibility assays have been performed through primary and secondary cell adhesion, cytotoxicity and murine peritoneal macrophage activation experiments. The DLN films show novel properties as potential biomaterials for coating bone implants and similar prosthetic which are subject to high friction and wear. They are being further developed to allow on-surface bone tissue engineering thus allowing ready acceptability into body implants and lowering the chances of immunogenic responses.